Present design of medium and large caliber explosive projectiles require that a cavity be formed in the main or bursting explosive charge for receiving a supplementary charge or a long intrusion fuze. Heretofore, this cavity has usually been formed either by deep-drilling the main explosive charge after the latter has been poured while molten into the projectile housing and solidified or by use of a long-stemmed pouring funnel during explosive pour and a subsequent facing operation. In the latter method, the long-stemmed funnel is inserted into the open nose of the projectile housing, the molten explosive material is poured and cooled to a solid state, the funnel is removed, and the bottom of the cavity is then formed by the facing operation. After the cavity is formed, a cup-shaped metal liner is manually inserted and fixed in place in the cavity, as by swaging the outer end into the threaded opening in the housing.
These methods are hazardous to personnel involved, because the drilling in the first method and the facing and swaging operation in the second method are likely to cause detonation of the explosive material. Moreover, both methods require cleaning to remove residual cutting fragments, which is also hazardous.
For the protection of facilities, equipment and personnel, the prior methods rely on control, rather than elimination of hazardous operation. The measures used to control hazards include visual inspection for explosive contamination of projectile threads and isolation or barricading of the hazardous operations of drilling, thread cleaning, cavity facing and liner swaging. Such measures not only are not completely effective but also add to the cost of manufacturing the projectile.
An object of the present invention is to provide a method of forming a cavity in an explosive charge that eliminates or avoids the hazardous operations of thread cleaning, cavity facing and drilling, and the possibility of explosive hazard during liner swaging. Another object is to reduce the numbers of inspections that are required. A further object is to improve the quality of the product.
In accordance with the present invention an open-ended metal liner is inserted into and rigidly secured to the open end of a projectile housing prior to explosive pour, the stem of a long-stemmed funnel is inserted into the liner until the lower ends are flush with each other, with a liquid-tight seal between the lower ends, molten explosive material is poured into the funnel to fill the housing and funnel to a level above the liner and allowed to cool to a solid state, and the funnel is then rotated to shear the material at the lower end and removed from the liner and housing. Subsequently, a closure disc is secured in the lower end of the liner.